qemu_v8: use "-machine acpi=off" instead of "-no-acpi"

Address the following warning:

 $ make run
 [...]
 qemu-system-aarch64: -no-acpi: warning: -no-acpi is deprecated, use '-machine acpi=off' instead

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/qemu_v8.mk b/qemu_v8.mk
index 89de524..92702e0 100644
--- a/qemu_v8.mk
+++ b/qemu_v8.mk
@@ -474,13 +474,13 @@
 		-nographic \
 		-serial tcp:localhost:54320 -serial tcp:localhost:54321 \
 		-smp $(QEMU_SMP) \
-		-s -S -machine virt,secure=on,mte=$(QEMU_MTE),gic-version=$(QEMU_GIC_VERSION),virtualization=$(QEMU_VIRT) \
+		-s -S -machine virt,acpi=off,secure=on,mte=$(QEMU_MTE),gic-version=$(QEMU_GIC_VERSION),virtualization=$(QEMU_VIRT) \
 		-cpu $(QEMU_CPU) \
 		-d unimp -semihosting-config enable=on,target=native \
 		-m $(QEMU_MEM) \
 		-bios bl1.bin		\
 		-initrd rootfs.cpio.gz \
-		-kernel Image -no-acpi \
+		-kernel Image \
 		-append 'console=ttyAMA0,38400 keep_bootcon root=/dev/vda2 $(QEMU_KERNEL_BOOTARGS)' \
 		$(QEMU_XEN) \
 		$(QEMU_EXTRA_ARGS)